Bartolini weak magnetic field pups

I have a 1985 bass with Bart JJs and I notice 2 thing that is not usual.
First the magnetic strength from both pups are much weaker compare with my newer Bart JJs. Next is that when I play it on passive mode, the output is very low too.
Since I just have this bass so I don't know if it was design like this when they made it or not so I wonder if the pups on this bass are expired.